Amplifier units are being used e.g. directly at the top of an antenna mast or tower in cellular mobile telephone systems. Such an amplifier unit is a critical component in the overall system and it is very important that it is operable at all times. Thus, even if the amplifier unit becomes inoperable for some reason, the signal must be passed on somehow to the base station located adjacent to the bottom of the antenna mast or tower.
It is previously known to connect a bypass segment in parallel to the amplifier in combination with switching means whereby the bypass segment is activated in case any of the amplifier transistors break down or the feeding power to the amplifier is interrupted.